Circuit breaker



June 22, 1943 T. LlNDsTRoM ETAL 2,322,301

C IRCUIT BREAKER June 22, 1943 T. LlNDsTRoM ETAL CIRCUIT BREAKER Filed DBC. l5, 1941 jy 203 zo/ 27/ fnfwef/Qn WITNESSES:

2 Sheets-Sheet 2 INVENTORS and ` ATTO EY Patented vJune 22,: y1943 CIRCUIT BnEAxEa Turc Lindstrom, Edgewood, and John W. May, Pittsburgh, Pa., ass'ignors to Westinghouse Electric 48; Manufacturing Company,

East

Pittsburgh, Pa., a corporation o! Pennsylvania Application December 13, 1941, Serial No. 422,786

(Cl. 20o-89) 13 Claims.

This invention relates to circuit breakers in general and more particularly to circuit breakers of the trip-free type for controlling moderate power circuits.

An object of the present invention is the provision of a trip-free circuit breaker having a trip device operable in response to predetermined conditions, and a latch operated to automatically latch the trip device in operated position.

Another object of the invention is the p rovision of a circuit breaker in which a toggle is operated by a trip device to cause opening of the breaker and in which a latch is operated upon operation of the trip device to restrain said trip device and the toggle in operated position and thereby prevent closing of the breaker.

Another object of the inventionv is the provision of a circuit breaker having an electroresponsive trip device which is adapted to be automatically locked in operated position when it is operated in response to an overload current.

Another object of the invention is the provision of a circuit breaker having a trip device including a trip member operable in response to overload currents to cause opening of the breaker, and having a latch which is automatically effective to latch the trip member in operated position upon operation of the trip member, said latch being manually operable to release the trip member.

Another object `of the invention is the provision of a circuit breaker in which the trip device is latched in operated position to prevent closing the breaker the trip device being manually releasable to permit closing the breaker.

Another object of the invention is the provision of a circuit breaker in which operation of a trip device causes operation of a latch member /to prevent closure of the breaker, the latch being manually operable to release the trip device and permit closing the breaker.

' Another object of the invention is the provision of a circuit breaker having a closing means for closing the breaker, a member movable to cause opening of the breaker irrespective of the position of the closing means and which must be reset to permit closing of the breaker, a trip device operable-in response to predetermined conditions to move the member, and latching means automatically effective to lock the trip device and member in operated position to thereby prevent closing of thebreaker.

Another object of the invention is the provision of a circuit breaker having a means which tion, together with additional advantages and is automatically effective to prevent closing of the breaker when the breaker is opened in response to predetermined conditions, said means being ineffective when the breaker is opened by other means.

Another object of the invention is the provision of a circuit breaker having a member movable to cause opening of the breaker and which must be reset to permit closing of the breaker, a plurality of trip devices each operable to cause movement of thelmember to cause opening of the breaker, and a'latching means automatically effective upon operation Vof one of the trip devices to prevent resetting of the said member.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operaobjects thereof, will be best understood from the following description of one embodiment thereof when read in conjunction withA the accompanying drawings, in which:

Figure 1- isa vertical sectional view through the center pole of a multiple circuit breaker embodying the principles of the invention; and

Fig. 2 is a horizontal sectional View of the trip mechanism.

Referring to Figure 1 of the drawings, the circuit breaker is provided with an operating mechanism common to all of the poles which is mounted in a U-shaped main frame I6 comprising a pair of frame members I'I (only one being shown) rigidly connected by a cross member I9. The frame I6 is mounted on the central portion of a base II of insulating material and is secured thereto by means of bolts 2| and 23. The outer ends of the frame members Il are rigidly connected by a cross member 25.

The bolt 23 extends through the base and the cross member I9 and serves to rigidly secure a connector 21 of conducting material to the cross member and to the base II. A shaft 29 extending through an opening in the connector 21 and through openings in the frame members I1 pivotally supports a pair of arms 3| having their free ends integral with a contact arm 30 for the center pole. The contact arms 30 (Fig. l) for the outer poles are identical with the arm 30 for the center pole but Vare not provided with arms The contact arms for the outer poles are rigidly secured to a tie bar 61 which extends across all of the poles and which is clamped to the center pole contact arm 30 by means of a split clamp l0 and a screw 1I. The three contact arms 30 are thus mechanically connected for movement together. Rectangular tubes B9 of insulating material between the tie bar 51 and contact arms 30 for the several poles serve to insulate the three movable contact arms and their associated contacts from the tie bar 61.-

The movable contact structures and the stationary contacts for the several poles are alike for which reason only the contacts for the center pole will be described. The contact arm 30 for the center pole pivotally carries a main movable Contact member 41 and a movable arcing contact member 55. The main contact member 41 is pivoted on a pivot pin 49 supported in projections ofthe contact arm 30, and the movable arcing contact member 55 is pivoted on a pivot pin 51 supported in projections 59 of the arm 30. The main movable contact member 41 carries a contact 33, and a contact 35 is secured to the arcing contact member 55. These contacts 33 and 35 are adapted to engage respectively xed contacts 39 and 31 secured on a conductor 4| which is in turn secured to the base I I by means of bolts 43. The conductor 4| extends upwardly and is bent at right angles, the bent portion extending through an opening in the base t form a terminal connector 45.

A spring 53 compressed between a spring seat on the contact arm 30 and a spring seat on the main contact member 41 provides contact pressure for the main contacts 33-39 when the contact arm is in the closed position. Contact pressure for the arcing contacts 35-31 is provided by a spring 53 surrounding a rod 6| pivotally connected to the arclng contact member 55 and slidable through an opening in a spring seat on the contact arm 30. The spring 63 is combetween the base and each of these connectors in order to align the members 21 of the outer poles with the corresponding member 21 for the center pole. A conductor 8|, secured to the connector 21 by means of bolts 14 extends clownwardly therefrom and is bent at right angles. The horizontally disposed portion of the conductor extends between the legs of a U-shaped tripping magnet core IBI and projects through an opening in the base where it forms a terminal connector 83 which, together with the terminal connector 45, serves to connect the breaker in an electrical circuit.

The electrical circuits for the several poles of the breaker are essentially the same, therefore, only the circuit for the center pole will be traced. This circuit extends from the terminal connector through the conductor 4|, the main contacts 33-39, the main contact member 41, the flexible shunt conductor 19, the connector 21, the conductor 8| to the terminal connector 83. The circuit for the arcing contacts, 31-35 extends from the terminal connector 45, through the conductor 4|, the arcing contacts 31-35, contact member 55, the flexible shunt conductor 11, the main contact members 41, and through the previously described circuit to the terminal connector 83.

The contact arms 30 are biased in a clockwise or opening direction by means of a pair of springs 85 (only one being shown). These springs are tensioned between the center pole contact arm 30 and a xed pivot 81 supported in the main frame I5. In the closed position of the breaker, the center pole contact arm 39 and consequently all of the contact arms are releasably restrained \in closed contact position (Fig. 1) by means pressed between a washer 55 seated on a' shoulder on the rod 6| and the spring seat on the contact arm 30. The rod 6| has a nut 15 on the outer end thereof which acts to limit counterclockwise rotation of the arcing contact member 55 about its pivot when the contact arm 30 is moved to open the contacts. Counterclockwise movement of the main contact member 41 is limited by a projection 13 thereon strik ing the body of the contact arm 30. The adjustment of the nut 15 on the rod 6| is such that the arcing contacts 35--31 open after the main contacts 33-39 open during an opening operation of the circuit breaker, and close before the main contacts close during a closing operation.

When the contact arm 30 is operated to open the contacts, the arc across the arcing contacts 35-31 resulting from the rupture of the current is drawn into an arc extinguisher indicated generally at 15 where it is cooled and extinguished. Any suitable arc extinguisher may be employed, the one illustrated comprising, generally, a stack of slotted plates (not shown) or magnetic mate rial disposed adjacent the paths of travel of each of the arclng contacts 35. The plates serve to draw the arc towards the ends of the slots where it is broken up into a plurality of short yarcs which are quickly cooled and extinguished.

The movable arcing contact member 55 is connected by a flexible shunt conductor 11 to the main contact member 41 and another ilexible shunt conductor 19 connects the main contact member 41 to the connector 21. The connector 21 for the center pole is secured to the cross member I9 of the frame I6 by the bolts 23, and the connectors 21 for the outer poles are bolted to the base with a spacer (not shown) of a toggle and linkage mechanism which is collapsible to cause opening of the contacts. The toggle and linkage forms a part of the common operating mechanism.

This collapsible linkage includes a lever B9 pivotally mounted on a xed pivot 9| supported on the main frame l5. The lever 89 comprises a pair of levers rigidly connected by an integral cross bar ||1, and is operatively connected to the support arms 3| of the center pole Contact arm 30 by a main operating toggle comprising toggle links 93 and 95. The toggle link 93 has one end pivoted on a pin ||l| supported on the lever 89 and the link 95 is pivoted on a pivot pin 99 on the arms"3|. The links 93 and 95 are pivotally connected by a knee pivot pin 91. The toggle link 95 comprises a pair of links rigidly connected by means of an integral cross bar 5.

The free end of the lever 89 is pivotally connected by means of a link |03 to one arm of a lever |05 pivoted on the xed pivot 81. The other arm of the lever |05 is pivotally connected to a toggle link |01 of a tripping toggle comprising the link |01 and a toggle link |09. The link |09 is pivoted on a xed pivot ||3 supported on the frame IS and comprises a pair of links joined near the pivot ||3 by a yoke |23 provided with projections |25 and |21, The toggle link |01 comprises a pair of links connected by a yoke I9 having a bent portion to which is secured an extension |2| of insulating material. The toggle links 01 and |09 are pivotally connected by a knee pivot pin 'I'he purpose of the extension |2| is to cooperate with a part connected to a manually operable handle |4| to manually trip the breaker in a manner to be more fully described later. The lever |05 and the link |03 each comprise a pair of members rigidly connected by yokes substantially as illustrated.

The linkage justv described serves to releasably hold the contact assemblage including the movable contacts for all `o1 the poles of the breaker in closed contact position. In the closed position, the main voperating toggle 93--95 is overcenter above a line through the center of the pins 99-|0|, and a second toggle, one link of which comprises the overcenter links 93-95 and the other link of which comprises the lever 89, is overcenter above a line through the center of the pins 99 and 9|. The overcenter movement of the main operating toggle 93-95 is limited by the projecting end of thev link 93 engaging the cross bar I5 of the link 95.-

With the main operating toggle 93-95 and the toggle comprising the links 93-95 and the lever 99 in the overcenter position, as shown in Fig. 1, the springs 85 bias the lever 89 in a clockwise direction. Clockwise movement of the lever 89 however, is normally prevented by the tripping toggle |01| 09 which is overcenter to the left of a line through the center of the xed pivot I3 and the point of connection of the toggle link |01 with the lever |05.' The toggle |0`|-I09 is biased to its overcenter position by a spring |28 tensioned between the yoke ||9 and the ilxed pivot ||3. The overcenter position of the tripping toggle 01-I09 is adjustably determined by the projection |25 of the yoke |23 engaging an adjusting screw |29 in the cross member 25 of the frame. 'I'he tripping toggle |01|09 in its overcenter position, acting through the lever .|05 and the link |03, prevents clockwise movement of the lever 89 and consequently holds the movable contact assemblage in the closed conl tact position against the biasing influence of the springs 85.

The tripping toggle |01|09 is adapted to be moved overcenter outwardly in a direction to cause its collapse to effect opening of the contacts by means of an overload trip device indicated generally at |33 (Fig. 1). The trip device is operable in response to overload currents in the circuits of the breaker to actuate a trip rod |35 and cause collapse of the tripping toggle |01-I09, The trip rod |35 is slidable vertically through a shunt ytrip coil (not shown) enclosed in a casing |38 attached to the main frame I5. The shunt trip coil forms an additional tripping means for tripping the breaker. The shunt coil is adapted to be energized from a suitable source and in a manner well known in the art, to operate the trip rod and trip the breaker from a remote point.

When operated either by the shunt coil or by the overload trip device |33,- the trip rod |35 is thrust upwardly and strikes the projection |21 of the yoke |23 and rocks the toggle link |09 clockwise about the fixed pivot ||3. This movement of the link |09 causes collapse of the tripping toggle |01|09 permitting clockwise movement of the lever 89 which permits the springs 85 to rock the movable contact assemblage clockwise to open the contacts. l

The main operating toggle 93-95 does not immediately collapse but the force of the springs 85 applied through the contact arm- 30-3I and the main operating toggle causes collapse of the toggle comprising the links 93-95 andthe lever 89 which results in a clockwise movement of the lever 89. This movement is transmitted through the link |03 and the lever .|05 to complete the collapse of the tripping toggle lill-|09.

The clockwise or opening `movement of the contact arm'l is arrested by projections (not shown) thereon striking portions |31 of the frame members I1 of the main frame I8. At this time the rebound of the inertia of the main operating toggle 93-95 and the parts of the linkage 89, |03 and |05 starts the main operat- The contacts are closed manually by operation of the previously mentioned handle |4|. The handle is rotatably mounted in a bracket |43 of insulating material secured to the outer end of the main frame I8. operatively connected to the mechanism (not shown) operated by the handle is a link I5I. The lower end of the link |5| is recessed and straddles a pulley-shaped projection |53 rigidly secured on a cross member |41 rigidly connecting the outer ends of a pair of spaced contact closing levers |45. These levers are disposed on the outside of the frame I6 and are ,pivotally supported on the ends of the xed pivot 9| which project beyond the frame members The inner ends of the lever |45 are rigidly connected by a cross member |49. Spaced projections |52 extending from the center portion of the cross member |49 support a pivot'pin |51 upon which is rotatably mounted a roller |55.

The contacts are closed manually by clockwise rotation of the handle |4|. This movement of the handle, through connections (not shown) thrusts the link |5| downwardly and due to its engagement with the projection |53, rotates the closing lever'I45 in a clockwise direction. During this movement of the lever |45, the roller |55 engages the link 93 of the now collapsed main operating toggle 93-95 and moves this toggle to-its overcenter position. Since at this time the tripping toggle |01|09 has been restored to its overcenter position, rotation of the lever 89 is prevented and consequentlyI the force applied by the roller |55 to straighten the toggle 93-95 rotates the contact arm 30 counterclockwise to close the contacts and to tension the springs 85. The clockwise movement 0f the closing lever |45 moves the toggle 93-95 overcenter above the line 99- |0| so that the contacts are held in the closed A position until the breaker is again tripped.

Upon release of the handle |4I following a contact closing operation, a spring |59 tensioned between the closing lever |45 and the frame I6 restores the lever |45 in a counterclockwise direction. This movement ofthe lever |45 and the projection |53 thrusts the link I5I upwardly to restore the handle |4I to its neutral position.

The closing lever |45 may be operated to automatically close the contacts through the agency of a motor |39 (Fig. 1) mounted on a plate attached to the side of the frame I6. The motor |39 may be energized from any suitable source.

I When energized,the vmotor is adapted, through viously described manner. As soon as the roller |3| passes out of engagement with the arm |34, the spring |59 acts to restore the lever |45 to its normal position. The motor |39 is deenergized by a suitable limit switch (not shown).

The circuit breaker may be tripped manually by rotation of the handle |4| through a small angle in a counterclockwise direction from its neutral position. When the handle is rotated in tripping direction, a projection (not shown) on the link |5| engages the extension |2| on the yoke I9 of the toggle link |01 and rocks the link counterclockwise about its point of connection with the lever |05. This moves the tripping toggle |01|09 overcenter in a direction to cause its collapse and effects opening of the contacts in the previously described manner.

As previously stated, the trip rod |35 is operated to effect tripping of the breaker by means of a current responsive trip device |33. There is a trip device |33 provided for at least two of the poles of the breaker but since the trip devices are alike only the one for the center pole will be described.

The trip device includes the U-sliaped magnet core |6| and a frame comprising substantially parallel side members |63 rigidly connected at their outer ends by a yoke |65. The members |63 are provided with mounting feet |61, and bolts |69 extend through openings in the feet |61 and in the magnet core |E| and in the base to rigidly secure the core and frame to the base. A trip lever |13 is pivotally supported on a pivot |15 mounted in the frame |63. The trip lever |13 comprises a pair of spaced levers having an armature |19 secured to one end and being rigidly connected by a yoke |11 at the other end. The

trip lever |13 is biased against operation by the magnet IGI, by means oi a pair of springs l9l (Figs. 1 and 2) having one end secured to the yoke |11 and the other end attached to a vertically movable plate |93. I'he plate |93 cooperates with an adjusting screw |95 which is provided with a knurled head |91 bearing against the bottom side of a formed projection |99 of the yoke |65. Rotation of the screw |95 moves the plate |93 and thereby adjusts the tension of the springs |9| to vary the tripping point of the breaker. A scale plate 203, supported on spaced projections 20| of the yoke |65, bears indicia indicating the adjustment of the springs |9| or the tripping point of the breaker. Ain adjustable stop screw 205 provided with a lock nut 201 determines the open air gap of the magnet.

A trip bar |81 is rotatably supported in a bracket |89 secured to the casing |38 for the shunt coil. The trip bar extends across all of the poles of the breaker and is provided with an arm |85 for each pole, the center one of the arms being in alignment with the lower end of the trip rod |35. An adjusting screw |8| is mounted in each of the yokes |11 in alignment with the corresponding arm |85.

Normal rated current flowing through the circuit of the breaker. including the conductor 8|, causes slight energization of the magnet |6| but not suflicient to overcome the tension of the springs |9I. Upon the occurrence of an overload current above a predetermined value in the circuit of any pole, the flow of current through the corresponding conductor 8| causes energization ot the magnet suillclent to overcome the spring |9I and attract the armature |19 rocking the trip lever |13 counterclockwise. At this movement o! the trip lever |13, the screw |8| rotates the arm and the trip bar |81 in a clockwise direction and thrusts the trip rod |35 upwardly to trip the breaker in the previously described manner.

The construction of the circuit breaker as thus i'ar described with the exception of the trip device |33 is essentially the same as that fully disclosed in the copending application of John W. May and Ture Lindstrom, Serial No. 391,625, filed May 3, 1941, and assigned to the assignee of this invention.

In accordance with the present invention, a locking mechanism 2|| serves to automatically lock each trip device |33 in its actuated position when the trip device is operated in response to an overload condition occurring in any pole of the breaker. By locking the, trip device in its actuated position the tripping toggle |01-|09 is maintained in its collapsed condition. In this condition of the tripping toggle, it is impossible to close the contacts until the door |5 of the housing 3 is opened and the trip device released in a manner to be described later.

There is an independently operable locking device 2|| provided for each pole of the breaker and since the locking devices are alike only the one for the center pole (Fig. l) will be described. Each of the locking devices comprises a locking lever 2|3 pivotally supported intermediate its ends on a pivot pin 2|5 mounted in a support comprising a pair of plates 2|1 of insulating material. The plates 2|1 are disposed one on each side of one of the side members |63 of the trip device frame and are secured thereto by means of a rivet 2|9 and by the pivot |15 for the trip lever, the pivot |15 extending through openings in the plates 2|1. A tension spring 22| having one end hooked into an opening in the locking lever 2|3 and the other end anchored on a rod 223 supported in the plates 2|1 biases the hookshaped lower end 225 of the lever 2|3 into contact with the center portion of a flanged roller 221 of insulating material. The roller 221 is rotatably mounted on a rod 229 mounted in openings in the members |13 comprising the trip lever. Cotter pins 23| are provided in the rod 229 to prevent axial movement thereof relative to the trip lever. Axial movement of the roller 221 is prevented by engagement of the flanges thereon with the end 225 of the lever 2 i3.

The upper end of the locking lever 2|3 is pivotally connected by means of a pivot pin 233 to one end of a horizontally extending link 235. An elongated slot 231 in the other end of the link 235 engages a rod 239 common to all of the links 235 and carried in the lower ends of a pair of spaced levers 24| (Figs. 1 and 2). The levers 24| are pivotally supported on a pivot pin 243 mounted in a U-shaped bracket 245 rigidly secured by means of screws 241 to a plate 249 of insulating material which is mounted on the insulating bracket |43. The upper ends of the levers 24| are rigidly connected by means of a yoke 25| and a spring 253 compressed between a projection 254 and the yoke 25| and the base of the bracket 245 biases the levers 24| in a counterolockwise direction. The counterclockwise movement of the lever 24| is limited by the engagement of the rod 239 with the enlarged inner end 255 of a releasing rod 251 slidably mounted in an opening in the plate 249 and in the base of the bracket 245. Spring pilots 259 and 29| secured respectively to the projection 254 and to the base of the bracket 245 serve to retain the spring 253 in position.

vassaaaoi magnet lIBI in response to an overload current in thefcircuit o! any one of the poles o! the breaker attracts the armature `|19 and rocks the trip lever |13 in a counter-clockwise direction to -eilect tripping of the breaker. This movement carries the roller 221 upwardly to aposltion opposite to the -recess in the lower endl of the lever 2I3, whereupon the spring 22| acts to rotate the lever 2I3 clockwise aboutthe pivot 2|! and engages the hook-shaped lower end of the lever beneath the roller 221. This restrains the trip lever |13 in its actuated position against the force exerted by the springs ISI which tends to restore the trip lever to its normal position.

It will be remembered that when the trip lever |13 is actuated the screw III, acting through arm |85 on the trip bar |81, thrusts the trip rod |35 upwardly to move the tripping toggle |||1I||9 overcenter in a direction to cause its collapse and thereby cause opening of the breaker contacts. When the trip device is restrained in its actuated position by the lockinglever 2I3, the trip rod |35 is held in its raised position, and due to the engagement of the upper end of the rod with the projection |21, holds the tripping toggle |||1I09 in its operated position. Operation of the closing lever |45 in closing direction under this condition will straighten the operating toggle 93-95, but since the springs 85 are stronger than the spring |28 lever 89 will be rocked clockwise and through thefconnecting link |03 will rock the lever |05 clockwise to further the collapse of the tripping toggle. It will thus be seen that with the trip lever restrained in its actuated position, it is impossible to close theA breaker contacts.

When the locking lever 2 I 3 was actuated by the spring 22| upon operation of the trip lever |13, the link 235 was thrust toward the right, moving the left hand end of the slot 2.31 close to the rod 239. In order to operate the locking mechanism to release the trip lever, the releasing rod 251 is thrust inwardly by means oi a knob 263 secured to the outer end thereof. 'Due to the engagement of the inner end 255 lof lthe releasing'rod with the rocl 239, the inward movement of the rod 251 rocks the arms 23| clockwise. 1 This movement f thrusts the link 235 inwardly rotating the lockingl 1ever'2I3 counterclockwiseto free roller 221. The springs I9I immediatelyv restore the trip lever to its unoperated position. This permits the spring |28 to move the tripping toggle ||I1-.I|l9rto` its overcenter holding position and the breaker may then be closed either-manually by manipulation of the handle |l|| or automatically by means of the rotor |39 in the previously described manner.

When the trip lever |13 returns to its unoperated position, the center portion of the roller 221 is positioned in the path of the lower end of the lever 2I3 and restrainsthe lever and the link 235 in the positions in which they appear in Fig. 1. When the pressure is released from the, knob 263 the spring 253 expands and rocks the lever 23| counterclockwise restoring the rod 239 to the right hand end of the slot 231 and moving the releasing rod 251 outwardly until it is arrested by engagement of the enlargedend 255 thereof with the base plate of the bracket 245.

The locking mechanism for each pole is indean overload `condition in any one ofthepoles oi' v the breaker.

The locking means the overload trip devices |33 and is not effective to lock the breaker in open position when it is tripped open either manually or by operation o! the shunt trip device |38.

Since, as previously described, the circuit breaker is completely enclosed and locked in a cubicle at a point remote from the central station, it is desirable to provide means to indicate the condition of the breaker at the central station. To this end there is provided a plurality of signaling circuits each of which is closed upon actuation of the trip device for any one of the poles of the breaker. One of the circuits may be utilized to sound an audible signal at the centra1 station and another of which circuits may energize a visual signal indicating the particular circuit breaker in whose circuits an abnormal' condition has occurred. Neither the signaling devices nor the circuits therefor is illustrated herein since any well known signaling devices may be used.

In order to close the circuits, a plurality of bridging contacts 265 are provided for each pole oi the breaker. The bridging contacts for each pole are mounted on a block 261 of insulating material secured to the armature |19 of the corresponding trip device, by meansv of screws 269 (Fig. 2). Secured in the base II adjacent each of the bridging contacts 265 is a pair of projecting contact members 21| provided with terminal connections 213 projecting to the rear of the base. 'Ihe terminal connectors serve to connect the contacts 21| in the signal circuits. l

It is obvious that when the magnet I6| for any pole of the breaker is energized a predetermined amount in response to an overload condition, the armature |16 for that pole will be attracted and engage the corresponding bridging contact 265 with the contacts 21| and thus close the circuit to the signaling devices.

Having described a preferred embodiment of the invention in accordance with the patent statutes, it is to be understood that various..

, changes and modifications may be made therein without departing from some of the essential features of the invention. It is, therefore, desired that the invention be interpreted as broadly as'the prior art permits, and that it be limited only by what is expressly stated in the followl ing claims.

We claim as our invention:

l. A circuit breaker comprising relatively mov-A operated position upon operation of the trip member.

2. A circuit breaker comprising relativelymovable contacts, operating mechanism for said contacts, a trip device including a triplever operpendently operable whenever an overload occurs in the circuit for that pole to automatically prevent closing of the main contacts ofthe breaker following an opening operation in response to able to cause opening of the contacts, means biasing said trip lever against tripping operation, electroresponsive means operable in response to predetermined overload circuit conditions for operating said trip lever, and a pivoted latch biased to latching position and operable under the control Of the trip lever to engage a part movable 2II cooperates only with with said trip lever for restraining the trip lever in operated position against the force of said biasing means.

3. A circuit breaker comprising relatively movable contacts, operating mechanism for said con.. tacts, a trip device including a trip member operable to cause opening of the contacts, electroresponsive means operable in response to predetermined overload circuit conditions for operating said trip member, latching mea-ns biased to a latching position for latching the trip member in operated position, means on the trip member for normally restraining said latchlng means, in unlatching position when said trip member is in an unoperated position, said restraining means being operable upon operation of the trip member to permit movement of the latching means,I to latching position.

4. A circuit breaker comprising relatively movable contacts, operating mechanism including a toggle operable to cause opening of said contacts, a trip device including a trip member for operating said toggle, electroresponsive means operable in response to predetermined circuit conditions for operating said trip member, and a latch operable upon operation oi' the trip member to restrain said trip member and said toggle in operated position to thereby prevent closing of said contacts.

5. A circuit breaker comprising relatively movn able contacts,-operating mechanism therefor including a toggle operable to cause opening of said contacts, a trip device including a trip member for operating said toggle, an electromagnet operable in response to predetermined circuit conditions for operating said trip member, a latch member operable upon operation of the trip member to restrain said trip member and said toggle in operated position to thereby prevent closing of said contacts, and manually operable means for operating said latch member to release the trip member.

6. A circuit breaker comprising relatively movable contacts, operating mechanism therefor, a trip device including a. trip member operable to cause opening of said contacts, electroresponsive means operable in response to overload currents to operate the trip member, a latch member supported on a fixed member and operable to a latching position upon operation of the trip member to restrain said trip member in operated position, and means apart from said operating mechanism for operating said latch member to unlatching position to release the trip member.

7. A circuit breaker comprising relatively movable contacts, operating mechanism therefor including anoperating handle, a trip device including a trip member operable to cause opening of said contacts irrespective of the position of said handle, electroresponsive means operable in response to overload currents to operate said trip member, a latch member engageable with a part movable with the trip member for restraining said trip member in operated position, and manually operable means apart from said operating handle for disengaging said latch member from said part to permit resetting of the trip member.

8. A circuit breaker comprising relatively movable contacts, operating mechanism therefor, a trip device including a trip member operable to cause opening of said contacts, electroresponsive means operable in response to predetermined overload circuit conditions for operating said trip member, a latch member pivoted on a fixed pivot and biased to latching position, a roller mounted on the trip member, said roller normally cooperating with said latch member to restrain said latch member in unlatching position and said roller being operable upon operation of the trip member to cause said latch member to engage said roller and restrain the trip member in operated position thereby preventing closing of the contacts.

9. A circuit breaker comprising relatively movable contacts, operating mechanism therefor, a trip device including a trip member operable to cause opening ofthe contacts, electroresponsive means operable in response to predetermined overload circuit conditions for operating said trip ,memben a pivoted latch member biased to a latching position, a roller mounted on the trip member and movable therewith, said roller normally restraining said latch member in unlatching position and said roller being operable upon operation of the trip member to cause movement or the latch member to a latching position wherein it restrains the trip member in operated position, and a manually operable device for moving the latch member to unlatching position.

10. A circuit breaker comprising relatively movable contacts, closing means for closing the contacts, a member movable to cause opening of the contacts irrespective of the position oi the closing means and which must be reset to permit closing of the contacts, a trip device operable in response to predetermined overload conditions to move the member, and latching means automatically effective to lock said trip device and the member in operated position to thereby prevent resetting of said movable member.

1l. A circuit breaker comprising closing means for closing the breaker, a member movable to cause opening of the breaker which member must be reset to permit closing of the breaker, a plurality of trip devices each operable to cause movement of said member to cause opening of the breaker, and a latching means automatically effective upon operation of one of said trip devices to prevent resetting of said member, said latching means being inelective to prevent resetting of said member when said member is moved by other of said trip devices.

12. A circuit breaker comprising closing means for closing the breaker, a member movable to cause opening of the breaker and which must bc reset to permit closing the breaker, a plurality oi trip devices each operable to move said member l to cause opening of the breaker, latch means automatically engageable with one of said trip devices upon operation of said trip device to prevent resetting of said movable member, and means operable to disengage said latch means to permit resetting of 'the movable member.

13. A circuit breaker comprising separable contacts, closing mechanism for closing said contacts, a toggle operable to cause opening of said contacts irrespective of the position of the closing mechanism, said toggle being automatically resettable to permit closing of the contacts, a plurality of trip devices each operable to operate the toggle to cause opening of the contacts, and a latching means automatically effective upon operation of one of said trip devices to prevent resetting Of the toggle.

TURE LINDSTROM. JOHN W. MAY. 

